Recently, as an ink ribbon used for an impact-type printer, the conventional spool types have been decreasing in number and products wherein a long tape-like ink ribbon is folded and stored in a cassette have been increasing. However, in such ink ribbons, both ends are welded (adhered) by means of an ultrasonic welder and made into an endless-type product and the life of the welded part exerts an influence upon the life of the ink ribbon. Namely, as the ink ribbon receives impacts from a head pin of a printer during printing and is gradually destroyed, the welded part exhibits lower durability than that of the ordinary part of a base fabric. Especially in these days, with remarkable increase in speeding and impacting of printers, remarkable improvement of durability of the welded part of the ink ribbon has been earnestly desired.
As a means for improving durability of the welded part, a technology wherein a thermoplastic synthetic resin layer with a melting point lower than that of the base fabric was placed between two ink ribbons and was welded, was proposed in Japanese Patent Publication No. 13,431/1982. However, there existed still problems that the improvement of durability of the welded part was not practically sufficient even by this method and workability on welding was not good either. Namely, it is the present status that improvement of durability of the welded part to cope with speeding up and impacting of a printer has not been realized.